Higher wattage bulbs give two problems 1) If the headlamp glass is plastic it may melt with the extra heat (!) 2) A higher wattage bulb will take more energy from the generator - perhaps more than it could cope with. A larger battery would help things a bit, but if the generator can't cope with the extra load then it would simply take longer to go flat. If you do go ahead with a 65w bulb then look for a dimmer tail lamp, and perhaps the battery wouldn't have enough charge for the electric starter if the lamps were used for a while.
John
December 2007
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